Google AppEngine is a platform for hosting scalable web applications and services. It provides automatic scaling of resources and a pay-as-you-go billing model. The main components include a runtime environment for Java and Python, a static file server, and a scalable and flexible datastore. The datastore acts as the central database, storing entities which contain properties mapped to key-value pairs. Entities belong to kinds and each has a unique key. The Python API provides methods like put() and get_or_insert() for creating, retrieving, and deleting entities from the datastore.

1. Google
AppEngine
Zuhair Khayyat

2. What is it for?
● Web applications
● Real time dynamic applications
● Automatic Scaling
● resource agnostic
● "Pay As You Go" billing: CPU, Storage,
Network

3. Main Components:
● Runtime Environment:
○ Respond to web requests
○ Java and Python
● Static File Server:
○ Resources does not change in regular operation:
images, CSS, HTML and JavaScript.
● Datastore:
○ Work as central database.
○ Storing requests' data.
● Scalable Service:
○ Manage self scaling for all AppEngine components

4. Datastore:
● Application storage ==> Datastore entity.
● Datastore entity ==> properties
● property ==> <key,value>
● Datastore entity ==> named kind
● Different datastore entity has different
properties.
● Single property has multiple values
● Each Datastore entity ==> unique key
● Java: JPA and JDO

5. Datastore: Python API - put()
from google.appengine.ext import db
import datetime
class Book(db.Expando):
pass
obj = Book()
obj.title = 'The Grapes of Wrath'
obj.author = 'John Steinbeck'
obj.copyright_year = 1939
obj.author_birthdate = datetime.date(1902,
2, 27)
obj.put()

6. Datastore: Python API - put()
● get_or_insert():
○ obj = Book.get_or_insert('0143039431')
● delete ()